This invention relates generally to transport utensils, and more particularly it relates to a caster wheel for transport apparatus such as a shopping cart or the like which is adapted for being advanced on a sloping conveyor belt having longitudinally directed guiding grooves and ribs on its upper surface. The caster wheel is of the type which includes a swivel housing with a projecting axle upon which are independently supported for rotation two wheel discs adapted for engaging the longitudinal grooves on the conveyor belt. The swivel housing further supports a braking bracket having a braking shoe which upon engagement of the rolling surface of the wheel discs with the conveyor belt grooves abuts against the longitudinal ribs of the belt.
In multi-level supermarkets there are used conveyor belts for conveying carrying apparatuses particularly the shopping carts from one floor to another floor. The upper surface of the conveyor belt is provided with longitudinal ribs defining corresponding grooves therebetween. To prevent the shopping cart from rolling during its transport on the inclined conveyor belt the periphery of its rollers and caster wheels is provided with radially projecting rings which engage the grooves in the conveyor belt. These guiding rings upon entering the grooves lower the position of the center axis of the wheel relative to the conveyor belt and the braking shoe connected to the wheel housing comes to rest on the upper surface of the conveyor belt before the periphery of the guiding rings contact the bottom of the grooves. As a result, the braking member upon placing the shopping carts on the conveyor belt makes the wheels ineffective. In order to facilitate the entry of the guiding rings into the grooves of the conveyor belt, the guiding rings by themselves are relatively narrow and consequently the specific pressure of the point of contact of the guiding rings with the floor is relatively high especially when taking the curves and when placing the carts on the conveyor belt. For this reason the guiding rings on the wheel of the cart are subject to excessive wear and already after a relatively short time of usage the wheels of the cart have to be exchanged in order to insure a flawless operation of the cart. The wear on the wheels and caster wheels caused by driving the shipping carts on a curved path can be substantially reduced by employing rollers instead of wheels as described for example in the German Pat. No. 2,656,322. The caster wheel described in this patent includes two wheel discs supported independently from one another for rotation on an axle whereby the wheel discs are arranged on opposite faces of a swivel housing arranged between the discs. The braking arm is substantially an extension of the swivel housing and supports on its lower end a braking shoe. The wheel discs themselves are supported on the central axis only and spaced apart by the housing whereby the rims of the disc-shaped wheel discs are completely free. Due to the play resulting from the wear in the bearings of respective wheel discs it may happen that the distance between the wheel discs in the range of their face surfaces either increases or diminishes so that the marginal zones of respective wheel discs no longer fit into the grooves of the conveyor belt. As a consequence a reliable transport of shopping carts provided with the afore-described prior art caster wheels is no longer insured. In addition, the swivel housing of this prior art caster wheel represents a special structure of a split wheel which necessitates in the case of the changeover from conventional shopping carts to those suitable for being transported on the inclined conveyor belt the changeover not only of the running wheel but of the entire caster wheel assembly.